Tongs for handling heavy products



Sept. 1968 G. A. JEAN-MARIE MARTELEE 3,

TONGS FOR HANDLING HEAVY PRODUCTS Filed July 11, 1967 United States Patent 3,401,974 TONGS FOR HANDLING HEAVY PRODUCTS Ghislain Antoine Jean-Marie Martelee, 71 Quai de Rome, Liege, Belgium Filed July 11, 1967, Ser. No. 652,511 Claims priority, application Belgium Aug. 19, 1966,

' 41,036, Patent 685,783

8 Claims. (Cl. 294-410) ABSTRACT OF THE DISCLOSURE Tongs for handling heavy products which are inherently rigid or which are placed on a rigid support comprise gripping jaws articulated to scissors-wise crossed arms which are articulated to the piston rod of a principal hydraulic jack and to a collar which is slidable and rotatable on said jack which is connected toa first pressure gas accumulator, the closing and opening of said arms being effected by means of an auxiliary jack the feed of which is controlled by a first electro-valve and comes from a second pressure gas accumulator which is also connected to said principal jack and possibly to a rotating jack via a second electro-valve which is telecontrolled by radioelectric signals like as said first electro-valve.

This invention relates to tongs for handling heavy products which are inherently rigid such as in particular metal sheets in rolls or bundles or which are placed on a rigid support.

In many fields of activity it is necessary to lift, convey and deposit heavy products. Thus, in metallurgy it is necessary to handle sheets in bundles or rolls, and for this purpose there have already been designed rack type tongs and tongs with swinging arms.

Rack-type tongs have a strong frame on which two arms with jaws slide under the action of a geared motor control system. With these tongs the clearance when in the closed position is determined by the width of the frame so that they can only be used where there exists between the rows of rolls, bundles or products to be handled, a distance greater than the said frame clearance. Furthermore with large size tongs the jaw arms are subject to considerable fiexional stresses causing friction which interferes with the sliding action, and the geared motor for opening the jaws is an expensive piece of equipment which necessitates an electric power supply by means of a cable placed on the winder.

In the case of tongs with swinging arms the jaws describe arcs of circles when closing. This calls for considerable skilfulness in carrying out the hooking-on operations, avoiding the jaws striking against the product to be handled. The electric motor mechanism for opening the arms has to be stronger and more powerful to stand up to very heavy loads so that the assembly becomes larger in size and the mechanism is more expensive.

Furthermore, like the other known tongs the latter are only usable in the vicinity of an electric power supply.

The object of this invention, which is intended to avoid the defects of known tongs, is to provide tongs for handling heavy products which are inherently rigid or are carried by a rigid support, which is characterized in that it has gripping jaws articulated to the ends of pairs of arms crossed scissors-wise whose other ends are respectively articulated to the piston rod of a principal hydraulic jack and to a mobile element on the said jack which is connected to a first pressure gas accumulator, the opening and closing of the arms and hence of the jaws being effected by means of an auxiliary jack the feed of which is controlled by a first electro-valve and comes from a second pressure gas accumulator likewise connected to Cal the principal jack and possibly to a tongs rotation jack passing via a second electro-valve.

In this way with each lifting effort of the tongs and the load the piston of the said principal jack descends and compresses in the said first accumulator the gas which, after the tongs are discharged from load, then restores its compressive energy and repels the piston which then compresses in the second accumulator the gas whose compression energy is then utilized to feed the auxiliary jack for opening and closing the jaws and possibly the jack for rotation of the tongs which thus acts quite independently of any external source of power but solely by the energy of the compressed gases in the accumulators which regenerate it at will in accordance with the control of the teleactuated electro-valves.

According to one feature the piston of the principal hydraulic jack is provided axially at one side with the rod to which the crossed arms are articulated and at the other side with a rod with grooves which fits in a socket with internal grooves driven by the rotation jack whose feed from the second gas accumulator is actuated by the second electro-valve.

According to another feature, in each pair of crossed arms one arm is articulated to a fixed point of the corresponding jaw while the other arm is articulated to a slider moving in a slide member provided in a shank in extension of the said jaw.

Furthermore the auxiliary jack for controlling the jaws is fixed on one of the said jaws and engages the slider moving in the shank of the said jaw.

According to another feature, the crossed arms are of the same length and are articulated to one another at their middles; the mobile element on the principal jack is a collar sliding on the cylinder of the said principal jack.

Other features will be clear from the following description of the attached drawings in which the figure is a diagrammatic view of a tongs made in accordance With the invention, represented by Way of non-restrictive ex ample.

In the tongs in question a principal hydraulic jack 1 has a cylinder 2 provided in its upper part with an attachment member 3 for suspending the tongs removably from a hook 4 of a lifting appliance (not shown). In the cylinder 2 there slides a piston 5 having, on one side, a driving rod 6 whose upper end is grooved and, on the other side a rod 7. There are articulated to the end 7:: of the rod 7 the inner ends of the arms 8a, 8b which are crossed scissors-wise with the arms 9a and 9b respectively, whose inner ends 9c and 9d are articulated to a collar 10 mounted slidingly and rotatively on the cylinder 2. The arms 8a and 9a and likewise the arms 8b and 9b are of the same length. There are articulated to the outer ends of the arms 9a and 9b the gripping jaws 11 and 12 which are extended respectively by the shanks 11a and 12a in which are hollowed out slides 11b and 12b. Sliders 13 and 14 can move in these slides, and to these sliders 13 and 14 there are articulated the respective ends of the arms 8a and 8b.

The chamber 2a of the cylinder 2 of the principal jack 1 which is filled with oil is connected via a duct 20 to a first gas accumulator 15 divided into two chambers 15a and 15b by a flexible diaphragm the chamber 15a contains oil and 15b contains a gas under pressure. When a heavy product is suspended from the jaws 11 and 12 and when the assembly is pulled upwards on the hook 4, the piston 5 compresses the oil in the chambers 2a and 15a which powerfully compresses the gas in the chamber 15b. When the heavy product has been deposited the compressed gas in the chamber 15b expands and expels the oil from the chamber 15a. Then the piston 5 rises entraining with it the rod 7 so that the arms 8a, 9a, 8b,

9b, the collar 10 and the jaws 11 and 12 rise. Above the piston 5 is a chamber 21) which is also filled with oil and which communicates on the one hand with an oil reservoir 16 via a duct 17 in which there is a non-return valve 17a and on the other hand with a chamber 180 of a second pressure gas accumulator 18, via a duct 19 in which there is a non-return valve 19a.

At the beginning of operations, after setting-up, the oil in the accumulator 18 is placed under pressure by the nitrogen which is under heavy pressure in a chamber 18b behind a piston 18a- A duct 20 leads from the duct 19 to a first electrovalve 21 at which there terminates a duct 22 going to the reservoir 16 which is under atmospheric pressure and ducts 23 and 24 respectively leading to the lower end and upper end of an auxiliary jack 25 controlling the opening and closing of the jaws 11 and 12. The rod 25a of the piston of the auxiliary jack 25 is articulated by its upper end to the extended end of the arm 85 whose slider 14 moves in the slide 1211. If by means of a telecontrol (not shown) and, for instance, by radio-electric signals, the electro-valve 21 is moved to the right against the action of a return spring 21a, the duct 20 is brought into communication with the duct 23 and the duct 24 with the duct 22 and the reservoir 16. Thus the oil coming from the chamber 180 of the gas accumulator 18 and undergoing the thrust of the gas under pressure in the chamber 18b, pushes the piston of the jack 25 upwards; the rod 25a rises so that the slider 14 rises and moves away from the jack 25. The angle of opening A of the arms 8b, 91] increases and the jaws 11 and 12 approach ing one another can grip between them a roll 31 placed horizontally, a pallet or a rigid bundle or any other rigid heavy product which can be raised. During the lifting operation the descent of the piston 5 causes the compression of the gas in the chamber b of the first accumulator 15 and the oil which is aspirated out of the reservoir 16, passing via 17a and 17, arrives in the chamber 21) above the said piston 5.

Once the roll is placed in the desired position, by means of radio-electric signals the valve 21 is actuated towards the left; thus the ducts and 24 are in communication and likewise 22 and 23 and the oil under pressure of the accumulator 18 acts via the ducts 20 and 24 on the upper surface of the piston of the auxiliary jack 2S, lowering the rod 25a and the slider 14. The angle A decreases and the jaws 11 and 12 spread apart, releasing the roll and the cycle of operations can begin again without it being necessary to supply any other feed of power to the tongs than that of the gas accumulators I which accumulate energy during some phases and give it up during others. As soon as the roll 31 is released the jaws 11 and 12 rise under the thrust of the gas compressed in 15b and the oil which being aspirated into the chamber 2b out of the reservoir 16 via the duct 17 is expelled via 19 and 19a into the chamber 18c of the second gas accumulator 18.

It is also possible to give a different orientation to the jaws, causing them to rotate round the longitudinal axis of the principal jack 1. For this purpose the grooved end of the driving rod 6 penetrates the grooved interior of a socket 26 integral with a rotary jack 27. This latter is connected to a second electro-valve 28 with control by radio-electric signals, at which there terminate ducts 29 and 30 respectively leading to the oil reservoir 16 and to the duct 19 and 20. According to the signals supplied the electro-valve 28 moves either to the right or to the left, against the action of a return spring 28a so that the oil under pressure coming from the chamber 180 of the accumulator 18, feeds via one or other of the ducts 30a, 3017, the rotary jack 27 which thus rotates in one direction or the other and likewise causes to rotate the socket 26, the driving rod 6, the piston 5, the rod 7 and, consequently, the crossed arms of the jaws of the tongs and the collar 10.

The tongs described have advantages of great importance. First of all it is automatic and removable and can be placed on various different hooks. Then, seeing that it operates with its own independent source of power, it has no connection with any outside source of energy. Furthermore, its construction and source of en rgy lend themselves very easily to telecontrol by radio-electric sig nals.

What I claim is:

1. Tongs for handling heavy products, inherently rigid or carried by a rigid support, such as rolls of metal sheets or bundles of metal sheets, comprising jaws which can be spread apart or brought together, two pairs of arms crossed scissors-wise, a principal hydraulic jack, a piston in said principal hydraulic jack, a rod rigid with said piston, a mobile element on said principal hydraulic jack, said jaws being articulated to the ends of said arms, said arms being articulated respectively to said rod and to said mobile element, a first pressure gas accumulator, a connection between said first gas accumulator and said principal hydraulic jack, an auxiliary jack for the opening and closing of said arms which spread apart and bring together said jaws, a second pressure gas accumulator, a connection between said second gas accumulator and said principal jack, a rotation jack for rotating the tongs, a connection between said second gas accumulator and said auxiliary jack, a first electro-valve on said connection between said second gas accumulator and said auxiliary jack, a connection between said second gas accumulator and said rotation jack, 2. second electro-valve on said connection between said second gas accumulator and said rotation jack, said first and second electro-valves being telecontrolled.

2. Handling tongs as claimed in claim 1, characterized in that said piston of said principal hydraulic jack is provided axially on the one hand with said rod to which the crossed arms are articulated and, on the other hand, with a driving rod with grooves which fit in a socket with internal grooves driven by said jack rotating the tongs; wherein the feed of power from said second gas accumulator is efiected via said second electro-valve.

3. Handling tongs as claimed in claim 1, characterized in that said principal jack is also connected to an oil reservoir.

4. Handling tongs as claimed in claim 1, characterized in that said mobile element on said principal jack is a collar mounted slidingly and rotatively on the cylinder of said principal jack.

5. Handling tongs as claimed in claim 1, characterized in that in each pair of crossed arms one arm is articulated at a fixed point of the corresponding jaw while the other arm is articulated to a slider movable in a slide provided in a shank extending the said jaw.

6. Handling tongs as claimed in claim 5, characterized in that said auxiliary jack controlling the opening and closing of the jaws is carried by one jaw and engages the end of one of said crossed arms which slides in the slide provided in the sank extending the jaw.

7. Handling tongs as claimed in claim 1, characterized in that said crossed arms are of equal length and are articulated to one another at their middles.

8. Handling tongs as claimed in claim 1, characterized in that said first and second electro-valves are telecontrolled by radio-electric signals.

References Cited UNITED STATES PATENTS 3,312,496 4/1967 Boutelle et a1. 2941l5 X 3,310,335 3/1967 Shuey 294-88 3,312,496 4/1967 Boutelle et al. 294- X EVON C. BLUNK, Primary Examiner.

R. D. GUIOD, Assistant Examiner. 

